1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 * 21 * Portions Copyright 2006-2008 John Birrell jb@freebsd.org 22 * 23 * $FreeBSD$ 24 * 25 */ 26 27 /* 28 * This file contains a reimplementation of the statically-defined tracing (SDT) 29 * framework for DTrace. Probes and SDT providers are defined using the macros 30 * in sys/sdt.h, which append all the needed structures to linker sets. When 31 * this module is loaded, it iterates over all of the loaded modules and 32 * registers probes and providers with the DTrace framework based on the 33 * contents of these linker sets. 34 * 35 * A list of SDT providers is maintained here since a provider may span multiple 36 * modules. When a kernel module is unloaded, a provider defined in that module 37 * is unregistered only if no other modules refer to it. The DTrace framework is 38 * responsible for destroying individual probes when a kernel module is 39 * unloaded; in particular, probes may not span multiple kernel modules. 40 */ 41 42 #include <sys/cdefs.h> 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 46 #include <sys/conf.h> 47 #include <sys/eventhandler.h> 48 #include <sys/kernel.h> 49 #include <sys/limits.h> 50 #include <sys/linker.h> 51 #include <sys/linker_set.h> 52 #include <sys/lock.h> 53 #include <sys/lockstat.h> 54 #include <sys/malloc.h> 55 #include <sys/module.h> 56 #include <sys/mutex.h> 57 #include <sys/queue.h> 58 #include <sys/sdt.h> 59 60 #include <sys/dtrace.h> 61 #include <sys/dtrace_bsd.h> 62 63 /* DTrace methods. */ 64 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 65 static void sdt_provide_probes(void *, dtrace_probedesc_t *); 66 static void sdt_destroy(void *, dtrace_id_t, void *); 67 static void sdt_enable(void *, dtrace_id_t, void *); 68 static void sdt_disable(void *, dtrace_id_t, void *); 69 70 static void sdt_load(void); 71 static int sdt_unload(void); 72 static void sdt_create_provider(struct sdt_provider *); 73 static void sdt_create_probe(struct sdt_probe *); 74 static void sdt_kld_load(void *, struct linker_file *); 75 static void sdt_kld_unload_try(void *, struct linker_file *, int *); 76 77 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 78 79 static dtrace_pattr_t sdt_attr = { 80 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 81 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 82 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 83 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 84 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 85 }; 86 87 static dtrace_pops_t sdt_pops = { 88 sdt_provide_probes, 89 NULL, 90 sdt_enable, 91 sdt_disable, 92 NULL, 93 NULL, 94 sdt_getargdesc, 95 NULL, 96 NULL, 97 sdt_destroy, 98 }; 99 100 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 101 102 static eventhandler_tag sdt_kld_load_tag; 103 static eventhandler_tag sdt_kld_unload_try_tag; 104 105 static void 106 sdt_create_provider(struct sdt_provider *prov) 107 { 108 struct sdt_provider *curr, *newprov; 109 110 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 111 if (strcmp(prov->name, curr->name) == 0) { 112 /* The provider has already been defined. */ 113 curr->sdt_refs++; 114 return; 115 } 116 117 /* 118 * Make a copy of prov so that we don't lose fields if its module is 119 * unloaded but the provider isn't destroyed. This could happen with 120 * a provider that spans multiple modules. 121 */ 122 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 123 newprov->name = strdup(prov->name, M_SDT); 124 prov->sdt_refs = newprov->sdt_refs = 1; 125 126 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 127 128 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 129 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 130 prov->id = newprov->id; 131 } 132 133 static void 134 sdt_create_probe(struct sdt_probe *probe) 135 { 136 struct sdt_provider *prov; 137 char mod[DTRACE_MODNAMELEN]; 138 char func[DTRACE_FUNCNAMELEN]; 139 char name[DTRACE_NAMELEN]; 140 const char *from; 141 char *to; 142 size_t len; 143 144 if (probe->version != (int)sizeof(*probe)) { 145 printf("ignoring probe %p, version %u expected %u\n", 146 probe, probe->version, (int)sizeof(*probe)); 147 return; 148 } 149 150 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 151 if (strcmp(prov->name, probe->prov->name) == 0) 152 break; 153 154 KASSERT(prov != NULL, ("probe defined without a provider")); 155 156 /* If no module name was specified, use the module filename. */ 157 if (*probe->mod == 0) { 158 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 159 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 160 mod[len - 3] = '\0'; 161 } else 162 strlcpy(mod, probe->mod, sizeof(mod)); 163 164 /* 165 * Unfortunately this is necessary because the Solaris DTrace 166 * code mixes consts and non-consts with casts to override 167 * the incompatibilies. On FreeBSD, we use strict warnings 168 * in the C compiler, so we have to respect const vs non-const. 169 */ 170 strlcpy(func, probe->func, sizeof(func)); 171 if (func[0] == '\0') 172 strcpy(func, "none"); 173 174 from = probe->name; 175 to = name; 176 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 177 len++, from++, to++) { 178 if (from[0] == '_' && from[1] == '_') { 179 *to = '-'; 180 from++; 181 } else 182 *to = *from; 183 } 184 *to = '\0'; 185 186 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 187 return; 188 189 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 190 } 191 192 /* 193 * Probes are created through the SDT module load/unload hook, so this function 194 * has nothing to do. It only exists because the DTrace provider framework 195 * requires one of provide_probes and provide_module to be defined. 196 */ 197 static void 198 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 199 { 200 } 201 202 static void 203 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 204 { 205 struct sdt_probe *probe = parg; 206 207 probe->id = id; 208 probe->sdtp_lf->nenabled++; 209 if (strcmp(probe->prov->name, "lockstat") == 0) 210 lockstat_enabled++; 211 } 212 213 static void 214 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 215 { 216 struct sdt_probe *probe = parg; 217 218 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 219 220 if (strcmp(probe->prov->name, "lockstat") == 0) 221 lockstat_enabled--; 222 probe->id = 0; 223 probe->sdtp_lf->nenabled--; 224 } 225 226 static void 227 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 228 { 229 struct sdt_argtype *argtype; 230 struct sdt_probe *probe = parg; 231 232 if (desc->dtargd_ndx >= probe->n_args) { 233 desc->dtargd_ndx = DTRACE_ARGNONE; 234 return; 235 } 236 237 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 238 if (desc->dtargd_ndx == argtype->ndx) { 239 desc->dtargd_mapping = desc->dtargd_ndx; 240 if (argtype->type == NULL) { 241 desc->dtargd_native[0] = '\0'; 242 desc->dtargd_xlate[0] = '\0'; 243 continue; 244 } 245 strlcpy(desc->dtargd_native, argtype->type, 246 sizeof(desc->dtargd_native)); 247 if (argtype->xtype != NULL) 248 strlcpy(desc->dtargd_xlate, argtype->xtype, 249 sizeof(desc->dtargd_xlate)); 250 } 251 } 252 } 253 254 static void 255 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 256 { 257 } 258 259 /* 260 * Called from the kernel linker when a module is loaded, before 261 * dtrace_module_loaded() is called. This is done so that it's possible to 262 * register new providers when modules are loaded. The DTrace framework 263 * explicitly disallows calling into the framework from the provide_module 264 * provider method, so we cannot do this there. 265 */ 266 static void 267 sdt_kld_load(void *arg __unused, struct linker_file *lf) 268 { 269 struct sdt_provider **prov, **begin, **end; 270 struct sdt_probe **probe, **p_begin, **p_end; 271 struct sdt_argtype **argtype, **a_begin, **a_end; 272 273 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 274 NULL) == 0) { 275 for (prov = begin; prov < end; prov++) 276 sdt_create_provider(*prov); 277 } 278 279 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 280 NULL) == 0) { 281 for (probe = p_begin; probe < p_end; probe++) { 282 (*probe)->sdtp_lf = lf; 283 sdt_create_probe(*probe); 284 TAILQ_INIT(&(*probe)->argtype_list); 285 } 286 } 287 288 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 289 NULL) == 0) { 290 for (argtype = a_begin; argtype < a_end; argtype++) { 291 (*argtype)->probe->n_args++; 292 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 293 *argtype, argtype_entry); 294 } 295 } 296 } 297 298 static void 299 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 300 { 301 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 302 303 if (*error != 0) 304 /* We already have an error, so don't do anything. */ 305 return; 306 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 307 NULL)) 308 /* No DTrace providers are declared in this file. */ 309 return; 310 311 /* 312 * Go through all the providers declared in this linker file and 313 * unregister any that aren't declared in another loaded file. 314 */ 315 for (curr = begin; curr < end; curr++) { 316 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 317 if (strcmp(prov->name, (*curr)->name) != 0) 318 continue; 319 320 if (prov->sdt_refs == 1) { 321 if (dtrace_unregister(prov->id) != 0) { 322 *error = 1; 323 return; 324 } 325 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 326 free(prov->name, M_SDT); 327 free(prov, M_SDT); 328 } else 329 prov->sdt_refs--; 330 break; 331 } 332 } 333 } 334 335 static int 336 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 337 { 338 339 sdt_kld_load(NULL, lf); 340 341 return (0); 342 } 343 344 static void 345 sdt_load() 346 { 347 348 TAILQ_INIT(&sdt_prov_list); 349 350 sdt_probe_func = dtrace_probe; 351 352 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 353 EVENTHANDLER_PRI_ANY); 354 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 355 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 356 357 /* Pick up probes from the kernel and already-loaded linker files. */ 358 linker_file_foreach(sdt_linker_file_cb, NULL); 359 } 360 361 static int 362 sdt_unload() 363 { 364 struct sdt_provider *prov, *tmp; 365 int ret; 366 367 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 368 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 369 370 sdt_probe_func = sdt_probe_stub; 371 372 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 373 ret = dtrace_unregister(prov->id); 374 if (ret != 0) 375 return (ret); 376 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 377 free(prov->name, M_SDT); 378 free(prov, M_SDT); 379 } 380 381 return (0); 382 } 383 384 static int 385 sdt_modevent(module_t mod __unused, int type, void *data __unused) 386 { 387 int error = 0; 388 389 switch (type) { 390 case MOD_LOAD: 391 sdt_load(); 392 break; 393 394 case MOD_UNLOAD: 395 error = sdt_unload(); 396 break; 397 398 case MOD_SHUTDOWN: 399 break; 400 401 default: 402 error = EOPNOTSUPP; 403 break; 404 } 405 406 return (error); 407 } 408 409 DEV_MODULE(sdt, sdt_modevent, NULL); 410 MODULE_VERSION(sdt, 1); 411 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 412